Today a major milestone was achieved with Zika virus: the establishment of a causal relationship between the virus and fetal abnormalities such as microcephaly. By now the world has been acting, appropriately, as if this was the case based on highly suggestive data. However, seeing the fidelity to causality in making the definitive case was heartening.

As philosopher Leonard Peikoff writes:

“The explicit identification of causality (by the Greeks) was an enormous intellectual achievement; it represented the beginning of a scientific outlook on existence, as against the prescientific view of the world as a realm of miracles or of chance.”

Causality is the hallmark of science--no appeals to correlations, suggestions, faith, "optics", or notion can supplant the need for causality. The CDC's New England Journal paper announcing the linkage does so with absolute deference to causality as exemplified by Shephard's Criteria.

Shephard's Criteria delineate what is required to establish the teratogenicity -- fetal malformation causation -- of a substance and Zika now unequivocally meets that threshold. With this development, the greenest light possible has been given to scientists to determine how to combat the virus.

Seeing such fealty paid to causality in an era when, unfortunately, logic is regarded as superfluous is remarkable.